Plate glass surfacing block



R. A. MILLER .Dm 15,v 1931.

PLATE GLASS SURFACING BLOCK Filed Sept, 2O, 1929 2 Sheets-Sheetv l Dec. 15, 1931. fR. A. MILLER PLATE GLASS SURFACING BLOCK 2 Sheets-Sheet 2 Filed `sept 2o, 1929 "lll'rllll'lll'lll' illl'llaulllll.

, INVENTOR @uw LM Patented Dec. l5, 1931 UNITED STATES 'PATENT OFFICE ROBERT A. KILLER, OF TARENTUM, PENNSYLVANIA, ASSIGNOR PITTSBURGH PLATE GLASS COMPANY, A CORPORATION OF PENNSYLVANIA PLATE GLASS SUBJAGING- BLOCK Application led September 20, 1929. Serialvlo. 3941075.

The invention relates to blocks for use in surfacing plate glass. In the continuous surfacing operation the glass plates to be surfaced are carried upon tables beneath driven surfacing units. The polishing units comprise runner frames in the form of spiders rotated by suitable driving means and carrying the polishing blocks mounted for universal movement upon spindles which are freely movable through the runner arms in a vertical direction. The centers of gravity of the polishing blocks lie Joelow their centers of universal support so that under the action of centrifugal force incident to the rotation of the runner frame at 'a` relatively high rate of speed, the block has a tendency to tilt, so that the polishing felt presses more lightly on the glass over the outer half` of its area than over its inner half. Under these conditions, (l) the polishing efficiency of the runner is reduced somewhat as compared with a block which presses evenly on the surface of the glass throughout the area of the block, and (2) the extreme margins of the sheet are not as well polished as the body of the sheet inside such margins.

The present invention is designed to overcome the tendency of the block to tilt under the action of centrifugal force, so that the block exerts a uniform pressure on the glass throughout its area. Certain embodiments of the invention are illustrated in the accompanying drawings, wherein:

Figure 1 is a verticalsection through one 3'5 of the improved blocks. And Fis. 2, 3, 4, and 5 are sections through modi cations.

Referring now to Figure l, which shows a block with the improvement applied thereto, 1 is a table carrying a glass sheet and movable on the usual track extending beneath the runner, one of whose arms 4 only is shown; 5 is the spindle of the block; 6 is the-block as a whole 7 is the body of the block of cast iron or other suitable material; 8 is the polishing felt having itsv edges turned up along the sides of the block and clamped" thereto'by means of the hollow ring 9; and 10 is a ball at the lower end of the spindle 5 fitting a socket in the top yof the plate 7 and held by means of theblock 11 in turn secured by the bolts 12. The center of gravity of this block 1s below the center of support of the block on the ball 1&0 so that under the action of cen-y trifugal force as the arm 4 rotates, the block normally tends to assume a tilting position.

To counteract this action, the ring 9 is provided lilled with a body of mercury 13. Under the action of centrifugal force due to the rotation of the runner arm 4 about its axis of rotation, the mercury in the ring 9 will move outward so that its major portion lies to one side of the vertical center lineof the block, thus weighting such side ofthe block so that it tends to tilt in a'direction which is the reverse of the tilting position above referred to. The quantity of mercury employed is just suiicient to counterbalance the tendency of the block to tilt,-so that when the runner is rotating at a normal rate of speed, the block with its mercury filled ring will normally occupy a horizontal position so that the pressure exerted over the face of the block will .be uniform throughout.

Fig. 2 illustrates a modification through which the same result is secured as in the construction of Fig. 1. Here the block 14 which holds the ball 10 is provided with an annular groove lcarrying the hub 15 of the arm 16, such arm being provided at its outer end with the weight 17. The bearing surfaces between the block 14 and hub 15 are provided with ball bearings 18, thus reducing friction to a minimum. In operation, centrifugal force will cause the weight 17 to move to the outer side of the block, thus counterbalancing the tendency of the block to tilt in the reverse direction, the weight here taking the place of the mercury in the ring 9 of the Fig. 1 construction. In other respects, this construction is the same as Fig. 1 except 90 that the slot ring 19 is .used instead of the hollow ring 9 of Fig. 1. s

Fig. 3 illustrates still another modifica- 'tion involving the eccentric mounting of the block so that the same result is securedL as in the constructions of Figs. 1 and 2. The ball 2O of the spindle 5 is o center with respect to the center line 2l of the body portion 22 of theblock, being mounted in a plate 23 rotatable in the block 22. This plate is held in position by means of the plates 24 secured by means of the screws 25 and anti-friction means are provided in the shape of the balls 26. In operation, centrifugal force tends to swing the block outward f-rom the cente of rotation of the runner arm, which counteracts the tendency of the block to tilt in the reverse direction, the result being thesame as that securedin the Fig. l construction.

Fig. 4 illustrates still another modification in which the body portion 27 of the block is provided with an integral pin 28, on iw, ich is swiveled the arm 29, and this arm 29 1s pro- -`-.vided with a socket forthe ball 30 of the spindle 31. Anti-friction bearings are provided in the form of the balls 32 and the arm is retained in position on the pin 28 by means of the plate 33 held by the stud bolt 34. The result secured here is the same as in t e Fig. 3 construction, the block tending to assume a position with the pin 28 on the side of the spindle 31 remote from the center of rotation ofthe runner when such runner is rotated.

The Fig. 5 construction approximates that of Fig. 3, an arm* 35 being pivoted on the spindle 36 and carrying a weight 37. lThe arm 35 is provided with a roller which engages the top of the block 39. The weight also applicable with surfacing blocks otherthan polishing blocks, such as grinding blocks, the only difference being in the abrading material which is supplied instead of polishing material and in the modified character of the surface which engages the glass.

What I claim is: y,

ting it to tilt and rotate and located above the center of avity of the block, a hollow ring carried y the block concentric with the center of support of the block, and a body of liquid partially filling said ring.

3. In combination, a surfacing block, a universal joint support for the block permitting it to tilt and rotate and located above` the center of gravity of the block, a felt sheet extending over the bottom of the block and having its edges turned up at the sides of the block, a hollow clamping ring vfitting over the edges of the felt and holding the felt to the block and a body of liquid partially filling said ring.

4. In combination, a spindle, a surfacing block mounted for tilting movement about the lower end of the spindle as a center, and provided with an annular chamber concentric with the spindle, and a liquid partially filling the chamber.

5. In combination, a spindle, asurfacing block mounted for tilting movement about the lower end of the spindle as a center, with its center of gravity below said center, and provided with an annular chamber concentric withthe spindle, and a liquid'partially filling the chamber.

6. In combination, a spindle, a 'surfacing block mounted' for-'rotary movement about the lower end of the spindle as a center and provided with an annular chamber concentric with the spindle, and a counterbalancing liqpid partially filling the chamber.

In combination, a support, a surfacing block rotatably and tiltably mountedv upon the support and a weight secured to the block to move about the axis of rotation thereof.

8. In combination, a support, a surfacing block rotatably and tiltably mounted upon the support ,and a mobile weight secured ,to the block to move about the axis of rotation thereof.

9. In combination, a support, a surfacing block rotatably and tiltably mounted upon the support and counterbalancing means mounted 1for movement about the center of the support and adapted to be urged out,- wardly by centrifugal force.

'In testimony whereof,` I have hereunto subscribed my name this 26th da of Jul 1929.

ROBERT MIL ER.

1*. In combination, a surfacing block, a uni-` yersal joint support for the block permitting 1t to tilt andl rotate and located above the center of gravity of the block,land counterbalancing means mounted for circular movement about the center of support of the block 

